March 16, 2011 08:57:27am
Re: update thread -- Japan's Nuclear 'accident'
Not to sound alarmist, but your BIL needs to be ready for a worst case scenario unfolding - that being a combination of:
1. A breach of core pressure vessel integrity allowing a compromised fuel matrix to be exposed to the environment. there is no doubt in my mind that the fuel has been damaged - whether it is a full meltdown or partial meltdown or blistering/rupturing of the fuel plate cladding really doesn't matter. What that does is expose very highly radioactive fission fuel products, fission by-products and activated fuel matrix compounds - stainless steel, carbon, inconel, etc. - to be exposed outside of normal fuel assembly boundaries. A meltdown or partial meltdown that is still contained within an intact core pressure vessel is relatively okay. But when the core pressure vessel integrity is compromised, damaged molten fuel can spill out. The immediate risk here is loss of shielding and subsequent high radiation levels which greatly complicates accident casualty control reponse. You could actually have pockets of criticality or supercriticality as the molten fuel slag rearranges itself into geometries that support sustained neutron generation and self-sustaining criticality. If the molten mix gets into the ground the immediate high radiation concerns still exist, but now you have to contend with the long term environmental impact - contamination of groundwater and eventually, concentration of various radioactive compounds into the food chain.
2. A fire involving the consumption of radioactive material - a possible scenario in unit #4 (possibly others) if the spent fuel storage pools are drained and the spent fuel can't be cooled. There are a lot of unknowns here - we don't know how much spent fuel is stored in the pools, how long the fuel has been stored and what the plant's operating history was prior to shutdown and fuel assembly removal. The longer the fuel has been in the storage pools the better. Most of the post shutdown high decay heat generation is gone within 100-120 days. There are several reports that the spent fuel in unit #4 was removed no earlier than 30 November when a regular refueling maintenance shutdown occurred. That puts us at 111 days maximum. Not ideal, but not bad - decay heat generation will be low. The problem is if the storage pools are losing water. Then the problem compounds - you have overheating fuel because the cooling water is gone AND even more significant, a loss of shielding and resultant high radiation levels. If water levels can't be restored, the spent fuel will heat up - how hot is dependent on a lot of variables, but in a worst case scenario, the spent fuel could melt, and possibly get hot enough to ignite surrounding materials. This would pump a lot of radioactive material into the air that could then be distributed by weather.
3. Winds anywhere from the north, easterly around to the south. Such weather would blow radioactive contaminants back onto land complicating immediate response with a considerable long term environmental impact. The best we could hope for is a nice high pressure to sit on top of Japan with continuous westerly winds blowing the whole mess out over the Pacific.
4. Any of the 3 events above by themselves complicate the current existing situation. Any combination of them is exponentially worse. The worst case scenario is if all three were to happen - and that remains a possibility.
I don't know where you BIL is, but having the following on hand allows him and his family to react quickly and add some degree of safety:
1. Enough fresh water and food so they don't have to go outside and get either food or water for a minimum of 1 week.
2. Some form of respiratory protection - even if is just a crude mechanical filtration like the masks so commonly seen in Japan.
3. Potassium iodide (KI) tablets in the event Iodine 131 is confirmed. KI saturates the thyroid with non-radioactive iodine which will prevent the uptake and concentration of I-131 in the thyroid which can cause thyroid cancer and other health issues. Check with your doctor before taking KI tablets - iodine supplements should only be taken in dosages consistent with recommended allowances, around 1100 mcg for an adult, less if you are younger, and exceeding this level can cause downstream health problems. This applies to a large dose OR a long term exposure to elevated doses. There are also several health conditions and medicine courses that are not compatibile with KI tablet consumption. Hypothyroidism and some high blood pressure meds fall into this risk category.
4. Some ability to seal his house/apartment if they can't leave. Duct tape, poly sheeting, etc. Turn off heating or cooling ventilation and wait it out.
I am stating the obvious, but the best thing is to not be where the plume was, is or is going. The reality is that some people don't have the ability to leave. The above measures are a bare minimum suggestion of some preparations that your BIL should do NOW, no matter where they live.
If you think I should make this a main thread topic I will be happy to repost for the benefit of anyone interested. It most certainly isn't Dead related, but I'm kind of going with the benevolent spirit approach that the community shares.